Above-ground testing methods – review of Rotorua, New Zealand test site results after ten years

RG/WP 18-20642

D Page, T Singh

A series of seven different types of above ground durability tests were initially conducted over four years to determine which type of tests would give the fastest, most consistent results. Five types of test; ground proximity, two types of decking, flat panels and double layer, were reassessed after ten years. Exposure conditions varied between tests with ground proximity producing close to ground-contact conditions, double layer test very wet conditions while raised decking and flat panel tests were relatively dry. The results indicated that the ground proximity tests gave the fastest results and rankings for different preservatives were similar to those for ground-level decking tests. Flat panels were the next most effective, followed by ground-level decking, double layer and raised decking. Results from the flat panel test appeared to be influenced by decay that was previously established in old CCA treated support framing. When resistance to decay was compared between preservatives, CCA was similar to spotted gum and better than any of the preservatives.

Keywords: double layer test, durability, flat panels, ground proximity, testing methods

Conference: 18-04-29/05-03 Johannesburg, South Africa

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